Visibility and movement: towards a GIS-based integrated approach

It is argued here that movement can only be fully experienced and, therefore, realistically modelled through integration with visibility. In this paper we explore a range of different approaches and techniques that investigate the characteristics of movement and visibility, the relationship between them and, importantly, how these are affected by changing scale. Using the ancient Ridgeway track in central England as a case-study, we first explore the idea of 'intentionality' within movement. This uses different sized windows of analysis to model 'looking ahead' and the idea of moving using waypoints as markers. In a related approach we develop Llobera's idea of landscape 'prominence' and introduce a new method, Fuzzy Cumulative Visibility Analysis (FCVA), which simulates a 'virtual walk' in the landscape by moving from cell to cell and calculating visibility in all directions. Some cells are seen more often than others in a continuously changing way and these changes can be expressed by a visibility index for each cell resulting in visibility gradients due to cumulative effects. This approach is novel in being applicable at a range of scales and is demonstrated through a case-study of Neolithic long barrows in central England. The approach to each barrow can be modelled in terms of visibility, distance and position to show interesting differences between basing these analyses on topography, prominence and FCVA. Building on this we continue with a re-assessment of the idea of 'Viewpaths' as first suggested by Lee and Stucky in 1998. This uses the notion that visibility is an actual 'cost' in influencing movement and is modelled by using forms and combinations of visibility indeces as cost surfaces for generating least cost paths, corridors and surfaces. Overall, this developing suite of approaches provides a much richer understanding of perceiving the landscape through movement and visibility than just viewsheds or cost paths.